1. Field of Invention
The present invention relates to a projector for forming a projected image by magnifying and projecting luminous flux emitted from a light source after modulating the luminous flux.
2. Description of Related Art
The number of environments in which projectors are used has recently increased. Apart from for presentations in office meetings or meetings on business trips, projectors are now also being used at technical meetings in research and development divisions, etc., for capturing CAD/CAM/CAE data therein in order to magnify and project the data, or at various seminars and learning courses. Projectors are also being used in school classes where audiovisual education is performed. Projectors are also being used for studying therapeutic methods and for performing medical guidance by projecting medical images and data, such as CT scans and MRI. Projectors are also being used for efficiently addressing numerous people gathered at exhibitions or conventions.
Presently, as projectors are being used in various environments, various requirements exist regarding the specifications and functions of projectors, such as light-weight compact models pursuing portability, high-luminance and high-resolution models pursuing image quality, and value-added models capable of connecting to various digital equipment and mobile tools.
Since further increases in the number of environments in which the projectors will be used is anticipated, more advanced value-added projectors are being vigorously developed in light of the new environments in which projectors will be used.
In any of these projector models, a cooling structure is provided with cooling air for cooling a heat-generating source, such as a light-source lamp, a power-supply unit, and a liquid-crystal panel. Specifically, cooling air is supplied from an air-inlet formed on an outer case by an air-intake fan, and the cooling air is exhausted outside from an air-outlet of the outer case by an exhaust fan after passing through inside the heat-generating source.
In such fans, an air-intake fan, used especially in the vicinity of the light-source lamp, has a rather larger size relative to air-intake fans for cooling other heat-generating sources and an exhaust fan, so that the entire light-source lamp, which is most liable to reach a high temperature in heat-generating sources, is securely cooled by a large amount of air-flow. Therefore, an axial-flow fan having a rotor with a large diameter may be frequently used as an exhaust fan for cooling the light-source lamp. Thus, a problem arises that large noises are generated due to the rotation of the fan.
In addition, noises generated during the rotation of the fan can be suppressed by using a sirocco fan instead of the axial-flow fan; however, the sirocco fan may reduce the cooling efficiency because it is liable to produce an air pressure that is lower than the air pressure of the axial-flow fan.
It is a first object of the present invention to provide a projector that is capable of cooling a light-source lamp efficiently and suppressing noises as well.
In addition to the light-source lamp, a driving circuit board that drives the light-source lamp is one of parts that is liable to reach a high temperature.
However, since the driving circuit-board is arranged adjacent to the light-source lamp, when a fan that is exclusively for the driving circuit-board is provided, both the fans are successively arranged, thereby increasing the projector size and the noises generated by the projector. Therefore, conventionally, the driving circuit-board is also cooled by the fan for cooling the light-source lamp in order to give preference to miniaturization and reduction in noises of the projector. This creates a problem that the cooling efficiency is lower than the cooling efficiency when the driving circuit-board and the light-source lamp are separately cooled by the respective fans.
It is a second object of the present invention to provide a projector capable of efficiently cooling internal elements, such as a light-source lamp adjacent to a driving-circuit board for the light-source lamp, in addition to the driving-circuit board, and moreover being capable of promoting the miniaturization and reduction in noises generated by the projector.
A projector according to the present invention includes a light-source lamp, a sirocco fan that exhausts cooling air to the base side of the light-source lamp, and an axial-flow fan disposed in the vicinity of the light-source lamp that exhausts the cooling air which is finished performing cooling. Luminous flux emitted from the light-source lamp is magnified and projected so as to form a projected image after being modulated.
In this application, xe2x80x9cbase sidexe2x80x9d is referred to as the side opposite to light-emergence.
In the light-source lamp, such as a metal-halide lamp which is frequently used in projectors, heat is generated in a light-emission portion which is set as a light source; a large amount of the heat is transferred to the base side therefrom and is radiated.
Accordingly, in the present invention, the base side of the light-source lamp is intensively cooled by the sirocco fan, while the exhaust fan is provided close to the light-source lamp so that the cooling air exhausted from the sirocco fan is allowed to quickly flow to cool the light-source lamp. Therefore, even when a sirocco fan in which the air pressure of cooling air is liable to be reduced is used, the heat generated in the light-source lamp can be smoothly radiated into cooling air, thereby efficiently cooling the light-source lamp. Since the sirocco fan is quiet compared to a conventional axial-flow fan, noises are suppressed to a low level. Thereby, a first advantage of the present invention is achieved.
In addition, in the present invention, an axial-flow fan is used to exhaust cooling air. Such an axial-flow fan may be a conventional fan. When the axial-flow fan is used, noises cannot be increased compared with those of a conventional projector. Moreover, advantages described above can be securely achieved by arranging the axial-flow fan in the vicinity of the light-source lamp.
In a projector according to the present invention, an air-inlet of the sirocco fan may be preferably arranged to face a driving-circuit board.
In such a structure, cooling air is allowed to pass through the driving-circuit board, for driving the light-source lamp, before being received by the sirocco fan, so that both of the light-source lamp and the driving-circuit board can be efficiently cooled solely by the sirocco fan. Since the driving-circuit board does not need an exclusive fan for cooling itself, miniaturization of the projector is promoted.
In a projector according to the present invention, the driving-circuit board may be preferably accommodated in a case member having a hole bored therethrough along the direction of the cooling airflow. In such a structure, since the driving-circuit board is accommodated in the case member capable of allowing cooling air to flow therethrough, the case member also serves as the duct covering the driving-circuit board. Therefore, cooling air is allowed to securely flow along the driving-circuit board, thereby enhancing the cooling efficiency of the driving-circuit board.
In a projector according to the present invention, a power-supply-circuit board may be preferably arranged adjacent to the driving-circuit board.
The power-supply circuit board is also liable to reach a high temperature. The power-supply circuit board is arranged adjacent to the driving-circuit board, so that cooling air for cooling the power-supply circuit board is allowed to smoothly flow by acceleration of the air due to the receiving action of the sirocco fan, enabling the cooling efficiency of the power-supply circuit board to be also enhanced.
In a projector according to the present invention, the power-supply-circuit board may be preferably arranged between the sirocco fan and another axial-flow fan that receives cooling air from the outside.
In such a structure, the power-supply circuit board is positively cooled also by the axial-flow fan, so that the cooling efficiency of the power-supply circuit can be further enhanced.
In a projector according to the present invention, the flow path between the sirocco fan and the axial-flow fan for the exhaust may be preferably provided with an opening for outwardly exhausting part of the cooling air exhausted from the sirocco fan.
In such a structure, the flow path between the sirocco fan and the axial-flow exhaust fan is provided with the opening for exhaust, so that the cooling air exhausted from the sirocco fan can be more efficiently exhausted through the axial-flow exhaust fan and the opening for exhaust. Therefore, although the flow rate of the sirocco fan may be increased, the axial-flow fan does not need to increase the flow rate thereof to enhance exhaust efficiency, so that by using the sirocco fan having a large flow rate, the cooling efficiency of the light-source lamp can be even further enhanced while maintaining a low noise level.
A projector according to the present invention includes a light-source lamp, a sirocco fan for use in internal cooling, and a driving-circuit board that drives the light-source lamp. Luminous flux emitted from the light-source lamp is magnified and projected so as to form a projected image after being modulated. An air-inlet of the sirocco fan is arranged to face the driving-circuit board.
In such a structure, in addition to the fact that the driving-circuit board is cooled by the cooling airflow caused by the receiving action of the sirocco fan, internal elements, such as the light-source lamp, can be also cooled by the cooling air exhausted from the sirocco fan. Since the sirocco fan is quiet compared to a conventional axial-flow fan that is rather large in size, noises are suppressed to a low level. Since the internal elements, such as the light-source lamp, do not need an exclusive fan for cooling them, miniaturization of the projector is promoted.
Preferably, a projector according to the present invention further includes another sirocco fan that exhausts cooling air toward the front face (front light-emergence side) of the light-source lamp.
In such a structure, optical elements disposed close to the front face of the light-source lamp are excellently cooled.